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Abstract

We analyzed temporal trends in mist-net capture rates of resident (n = 8) and overwintering Nearctic-Neotropical migrant (n = 3) bird species at two sites in montane broadleaf forest of the Sierra de Bahoruco, Dominican Republic, with the goal of providing quantitative information on population trends that could inform conservation assessments. We conducted sampling at least once annually during the winter months of January – March from 1997 – 2010. We found evidence of steep declines in capture rates for three resident species, including one species endemic to Hispaniola. Capture rate of Rufous-throated Solitaire (Myadestes genibarbis) declined by 3.9% per year (95% CL = 0%, 7.3%), Green-tailed Ground-Tanager (Microlegia palustris) by 6.8% (95% CL = 3.9%, 8.8%), and Greater Antillean Bullfinch (Loxigilla violacea) by 4.9% (95% CL = 0.9%, 9.2%). Two rare and threatened endemics, Hispaniolan Highland-Tanager (Xenolegia montana) and Western Chat-Tanager (Calyptophilus tertius), showed statistically significant declines, but we have low confidence in these findings because trends were driven by exceptionally high capture rates in 1997 and varied between sites. Analyses that excluded data from 1997 revealed no trend in capture rate over the course of the study. We found no evidence of temporal trends in capture rates for any other residents or Nearctic-Neotropical migrants. We do not know the causes of the observed declines, nor can we conclude that these declines are not a purely local phenomenon. However, our findings, along with other recent reports of declines in these same species, suggest that a closer examination of their conservation status is warranted. Given the difficulty in obtaining spatially extensive, long-term estimates of population change for Hispaniolan birds, we suggest focusing on other metrics of vulnerability that are more easily quantified yet remain poorly described, such as extent of occurrence.

Author Comment

This is a submission to PeerJ for review.

Additional Information

Competing Interests

The authors declare that they have no competing interests.

Author Contributions

John D Lloyd conceived and designed the experiments, performed the experiments, analyzed the data, contributed reagents/materials/analysis tools, wrote the paper, prepared figures and/or tables, reviewed drafts of the paper.

Chris C Rimmer conceived and designed the experiments, performed the experiments, wrote the paper, reviewed drafts of the paper.

Kent P McFarland conceived and designed the experiments, performed the experiments, wrote the paper, reviewed drafts of the paper.

Animal Ethics

The following information was supplied relating to ethical approvals (i.e., approving body and any reference numbers):

Banding activities were conducted by permission of the USGS Bird Banding Lab, under a permit issued to CCR, and research activities in the Dominican Republic were approved by the Subsecretaria de Áreas Protegidas y Biodiversidad.

Field Study Permissions

The following information was supplied relating to field study approvals (i.e., approving body and any reference numbers):

Banding activities were conducted by permission of the USGS Bird Banding Lab, under a permit issued to CCR, and research activities in the Dominican Republic were approved by the Subsecretaria de Áreas Protegidas y Biodiversidad.

Data Deposition

The following information was supplied regarding data availability:

KNB Data Repository. doi:10.5063/F1CR5R81.

Funding

Funding for our work over the years was provided by multiple sources, including the Carolyn Foundation, MacArthur Foundation, The Nature Conservancy, Stewart Foundation, Thomas Marshall Foundation, U.S. Fish and Wildlife Service, U.S. Forest Service International Program, and friends of both the Vermont Center for Ecostudies and Vermont Institute of Natural Science. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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